SPECTROPHOTOMETRIC METHODS FOR THE DETERMINATION OF TERBUTALINE IN PURE AND IN DOSAGE FORMS

Two simple, sensitive, rapid methods for the determination of terbutaline in pure and in dosage forms are developed. The first one (A) is based on condensation with sodium cobaltinltrite in aqueous acetic acid solution the colour of the complex product is measured at ʎ_max 422nm against reagent blank.
The second method (B) is based on the reaction of the drug with 4-amino antipyrine (4-AAP) in presence of buffer solution of potassium dihydrogen phosphate and oxidising agent potassium ferricyanide. The produced colour is measured at ʎ_max 490nm against reagent blank. Appropriate conditions were established to obtain maximum sensitivity.
The two proposed methods obey Beer's law over concentration ranges of 4-40µg ml^-1 and 10-50ug ml^-1 for A and B respectively. The apparent molar absorptivity and sandel sensitivity for method A is 4.070 x 10³ Lmol^-1 cm^-1 and 1.348 x10^-1 µg cm^-2, while for method B is 0.6 x 10⁴ L mol^-1 cm^-1 and 9.14 x10^-2 µg cm^-2.
The detection and quantification limits are calculated. The developed methods are applied successfully for the determination of terbutaline in pure and in pharmaceutical formulation without interference from common excipients.